Rumors circulating that Novell is going to kill off its popular Linux desktop lines are completely false. [However,] Novell is making one large strategic change. The GNOME interface is going to become the default interface on both the SLES and Novell Linux Desktop line. KDE libraries will be supplied on both, but the bulk of Novell's interface moving forward will be on GNOME. "The entire KDE graphical interface and product family will continue to be supported and delivered on OpenSuSE."

From everything I've read over the past few years it seems KDE has about 60 to 70% of the linux desktop market. I know I started out using Gnome and switched to KDE about somewhere around 3.0 with SuSE 8.
I always install Gnome and give it try every few weeks thinking maybe I'm missing something but in my opinion it just does not compare to KDE 3.4. Part of it is speed, part of it is control and customizability, and a lot of it is just the look and feel of the desktop.